Ideally a vibration signal will be free of any noise or interference that would hinder analysis. Unfortunately, this is never the case in the real world; there are always constant and uncontrollable changes to the vibration in a machine that add noise to the signal.…
read moreWe can measure vibration of a machine and generate a time waveform (time domain). Fast Fourier Transform (FFT) can then be performed to produce a spectrum (frequency domain). One thing to consider is FFT is performed on a block of samples, which are called the…
read moreA mechanical structure such as a beam attached at one end will oscillate at a particular frequency if it is knocked or set into motion; this is known as its natural frequency. Systems can have single or multiple degrees of freedom, depending on the number…
read moreEvery single rotor needs to be balanced. It is often difficult to decide which particular balancing method to employ, rotational speed for balancing to be used, acceptable vibration level for balancing to be met, etc. Fortunately, there are some general guidelines for balance quality in…
read moreSelecting appropriate measurement locations when collecting vibration data is important in order to determine the machine condition. Improper mounting locations often lead to gaps or omissions in the analysis, even when using the appropriate sensors, software setup and analysis techniques. The best locations for collecting…
read moreA transducer can be mounted in different ways. The way it is mounted can affect the frequency output. Each transducer is calibrated and its frequency response chart is supplied by the transducer manufacturer. The chart shows how linear the output is for a specific input.…
read moreTransducers transmit a continuous analog signal that has to be captured before any analysis or signal processing can occur. It is impossible and inefficient to record every bit of data being transmitted, and data collection hardware and software can be manipulated to take readings of…
read moreWhen taking vibration measurements it is important to verify that the data does not contain errors. Bad data can be caused by several factors including: poor cable connections, faulty sensors, mechanical and thermal shocks to the sensors, improper mounting conditions, and settling time. Most data…
read morePhase measurement is a very powerful tool in vibration analysis. Phase is a relative position of two or more signals. Let’s take an example of pendulums. Two pendulums are not “in phase” if one of them is going the other direction or not in harmony…
read moreTop left: Low pass filter. Top right: High pass filter.Bottom left: Band pass filter. Bottom right: Band stop filter. Vibration signal from a transducer requires signal processing to produce the data that we need. The process usually involves filtering, setting sample rates and resolution, windowing,…
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